1. Field of the Invention
The present invention relates to an air cushioned bed, and more particularly to a self inflated air cushioned bed having an expanding device received in each of the air units that form the air cushioned bed.
2. Description of Related Art
With reference to FIG. 10, an inflatable air cushion (80) disclosed in U.S. Pat. No. 4,541,136 and U.S. Pat. No. 5,111,544 has a base (82) and multiple air units (84) integrally formed and communicating with one another. The air units (84) are mounted on top of the base (82) so that the air inside the air units (84) provide a cushion to a load on top of the air cushion (80). Because the air units (84) are integrally formed, it is necessary for the manufacturer to use another mold to make another air cushion with different dimension, which increases the fabrication cost. Furthermore, although this kind of air cushion (80) is able to prevent the user from having bedsore, once the user, especially the elders, disables or sick ones, has bedsore, the user is not able to use the air cushion any more. Again, if there is any one of the air units is broken, the entire air cushion will have to be replaced, which shortens the life span of this air cushion.
To overcome the shortcomings, a second air cushioned bed is introduced. With reference to FIG. 11, the air cushioned bed has a base (90) and multiple air units (92) detachably mounted on top of the base (90) via a hook and loop combination (94). Preferably, the hook and loop combination is a Veloro(trademark). The provision of the hook and loop combination (94) allows each of the air units (92) to be removable relative to the base (90) so that the user is able to freely adjust the area without any of the air units (92). Each air unit (92) is independent to the others and has an air nozzle (not shown) on a bottom face of the air unit (92) so that the user is able to respectively inflate the air units (92) one by one. Although the user has the ability to rearrange an area without any of the air units (92), the user still has to go through a great deal of trouble to inflate each one of the air units (92), which is quite troublesome and labor inefficient. Besides, after a period of time using the air cushioned bed, the air pressure inside the air units (92) will gradually drop. Thus, there should be someone, the nurses, to help the needed ones. However, the routine nursing work load of the nurses is already tiring, if helping the needed to inflate the deflated air units (92), either the air cushioned bed will be crushed for lack of tending or the nurse will quit job for too much work load.
A U.S. Pat. No. 6,321,404B1 issued to Tsai on Nov. 27, 2001 disclosed multiple independent inflatable units each having four air cells integrally formed with one another. The manufacturer is able to use multiple units to make a cushion suitable for bed, chair, etc. It is noted that an air nozzle is formed on a bottom face of each of the units so that the user is able to use an air pump to inflate each of the units simultaneously or respectively depending on the design of the air pump. Although the patent does leave a large freedom to the user to decide how many units are required to cope with the object intended to have the units mounted onto the object, because the location of the air nozzle is located at the bottom face of the unit, the manufacturer will have to further design a further space for receiving air ducts from the air pump so as to inflate the units when required, thus the air cushion is thick, which causes problem when shifting and storage.
To overcome the shortcomings, the present invention tends to provide an improved self inflated air cushioned bed to mitigate and obviate the aforementioned problems.
The primary objective of the present invention is to provide an improved self inflated air cushioned bed having multiple air units removably mounted on top of a base. Each of the air units have therein an expanding device so that after a load originally on top of the air unit is removed, the expanding device is able to inflate the air unit automatically via a unidirectional valve.